The present invention relates to a mobile or wireless communications system and, more particularly, to channel state information (CSI) feedback in vertical and full-dimensional beamforming operations.
In the recent 3GPP standardization discussions, the vertical/elevation beamforming or its generalizations, full-dimensional (FD) beamforming has been considered as one promising technique for the future cellular systems to reduce the intra-cell and intercell interference and improve the per-cell average spectral efficiency. The vertical and FD or three dimensional (3D) beamforming has been agreed to be a study item in the 3GPP RAN1 standardization. In this invention, we consider the design of channel state information (CSI) reporting schemes to better support the vertical or FD beamforming. In particular, we provide several CSI reporting schemes that includes additional CQI/PMI computed under the assumption of post-scheduling intra-cell interference from other potentially co-scheduled users.